PLE133T is essentially 693A minus the AGP slot plus integrated Trident BladeXP graphics (warning: useless 3D!) and Tualatin support. 694T evolved from 693A by adding 4x AGP and Tualatin compatibility.
The southbridge might be the same 686B, or the quite similar 8231 which'll potentially get you integrated LAN. You choose. For a basic it-works thing, PLE133T is much more cost effective (but if I were you, I'd choose SiS 630ET for that!), for a better performing machine use the 694T or SiS 635T for that matter.